As a commercial heating engineer in Exeter, we at Exeter Heating can install either air source or ground source heat pumps for your business or non-profit. Air source and ground source heat pumps have certain advantages over other forms of heating, not the least of which is that in most cases they will save you money. Most importantly, they will reduce your carbon footprint and we all need to do whatever we can today in order to achieve that and keep global warming as low as possible.

The difference between the two is that an air source heat pump sources heat from the air, while the ground source pump uses heat from the ground. One of the advantages of an air source pump is that it does not require us to dig up your garden or install anything underground, and thus it is cheaper to install than a ground source heat pump. The air source unit looks very much like an air conditioning plant, so you will need a certain amount of outside space in which to install it. Whichever type of heat you use, it is essential to have the building properly insulated because otherwise some of the heat generated will be lost.

The pump is usually placed outside at the side or rear of a property and works by extracting heat from the air and boosting it to a higher temperature. It takes in air from outside to heat a liquid refrigerant. The pump does need electricity in order to run but should use less electrical energy than the heat that it produces. It compresses the liquid in order to increase its’ temperature and it then condenses back into a liquid to release the heat. This is then sent to your underfloor heating or radiators to heat the building while the rest is sent to a hot water cylinder. The water then is used for showers, taps, and so on.

There is another type of air-source heat pump which is known as air-to-air. This works by heating air rather than a refrigerant and feeding it into the building using fans. This type of heat pump cannot heat water.

Many air source heat pumps are eligible for a government grant under the non-domestic renewable heat incentive. The Energy Saving Trust calculates that the cost of installing an air-to-liquid, also known as air-to-water, heat pump for an average 4-bed detached home would be about £6,000 to £8,000. Obviously, this could be a lot more depending upon the size of your business property. However, the savings on energy costs could also be a lot bigger.

Working on the figures for a 4-bed detached home, The EST calculates that the following annual savings could be made, depending on what sort of heating system you are replacing. Annual savings for replacing an old (G rated) gas boiler would be £400 – £465. Replacing an old (G rated) oil boiler would be £460 – £545. Replacing old electric storage heaters would be £800 – £990, and replacing an old (G rated) LPG boiler would be £1,135 – £1,450. On top of that, the annual domestic renewable heat incentive payments from the government would be between £875 – £1,030.

However, if you are replacing a new A-rated system, an air source heat pump could actually work out a little more expensive. Replacing an A-rated gas boiler would increase bills by £35 – £55 while replacing an A-rated oil boiler would increase the bill by £45 – £55 per annum.

Air source heat pumps will certainly reduce your carbon footprint, but they do require electricity to run them so they cannot be considered zero-carbon unless the electricity is provided by solar power or a wind turbine. However, they will produce less CO2 than a conventional heating system. They are much easier for us to install than a ground source heat pump because we won’t need to do any digging or lay any pipes in the ground. They may also be fairly noisy and pump out cold air in the immediate vicinity of the pump.

The good news is that by replacing an old system with air source heat pumps you should be eligible for the non-domestic renewable heat incentive which is paid quarterly over a 20-year period based on the amount of heat generated.